The primary objective of the proposed research is to elucidate the nature of involvement of vitamin E and selenium in the modulation of enzymatic oxidation of arachidonic acid (AA) via the cyclooxygenase and lipoxygenase pathways. To gain further knowledge on the precise mechanism(s) of vitamin E and selenium-dependent antioxidant defense functions, 03 is employed an a model oxidant for the investigation of the biochemical and immunological consequences of oxidant stress under E/Se deficiency. The hypothesis to be tested is that an oxidant stress, such as that found in the E/Se deficient state, can perturb enzyme activities as well as the product profile of the AA cascade. These AA metabolites may play an important role in the pathophysiology of oxidant-induced lung damage. Accordingly, we propose to examine the effects of O3 exposure in rats under E deficiency, Se deficiency or both on: 1) the levels of lipid peroxides and other TBA reactive products in lung and blood; 2) the status of thromboxane A2-prostacyclin I2 homeostatis; 3) the formation of prostaglandins, F2 alpha, E2 and D2, and the enzymes involved in their biosynthesis, in this case, the glutathione S-transferases; 4) the leukotrienes and the enzymes involved in their biosynthesis, particularly the 5- lipoxygenase and the glutathione S-transferases; 5) the capacity of lung to metabolize arachidonic acid in vitro; 6) the potential for AA-dependent lipid peroxidation and cooxidation of benzopyrene-7, 8-dihydrodiol of lung and 7) pulmonary alveolar macrophage functions. The research methods to be employed include spectrophotometric and isotopic assays for the measurement of enzyme activities, radioimmunoassays, liquid scintillation spectrometry, GC/MS, thin-layer, and high pressure lipid-chromatographic techniques for the analysis of prostaglandins and leukotrienes. New information to be derived from the proposed effort should deepen our understanding of the role of vitamin E and selenium in modulation of the cyclooxygenase and lipooxygenase pathways.